# GTB-5550

Source: https://onco.cc/drugs/gtb-5550/  
OnCo record `gtb-5550` (Treatment). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

GTB-5550 is a protein from GT Biopharma, given as an injection under the skin, that wakes up natural killer cells and points them at tumour cells carrying the B7-H3 marker. It is in a first trial in several solid tumours.

## Summary

GTB-5550 is GT Biopharma's dual-nanobody TriKE against B7-H3. Its phase 1 basket trial (NCT07541573) dosed the first patient in May 2026; up to six dose levels are tested before expansion cohorts in castration-resistant prostate, ovarian, breast, head and neck, non-small cell lung, pancreatic and bladder cancer. In September 2026 the company announced multiple myeloma as a potential further indication.

## Fields

- Kind: Treatment
- Status: phase-1
- Last checked: 2026-11-04
- Also known as: GTB-5550 TriKE
- Tags: pipeline
- Code: GTB-5550
- Modality: Tri-specific natural killer cell engager (dual camelid nanobody, subcutaneous)
- Mechanism: A single-chain fusion of a camelid nanobody against CD16 on natural killer cells, wild-type IL-15, and a camelid nanobody against B7-H3 on tumour cells, as described by GT Biopharma.

## Sources

- GT Biopharma: product pipeline: https://www.gtbiopharma.com/product-pipeline/overview
- ClinicalTrials.gov: NCT07541573: https://clinicaltrials.gov/study/NCT07541573

## Connected records

- technologies: [NK cell engagers](https://onco.cc/technologies/nk-cell-engagers/)
- targets: [B7-H3](https://onco.cc/targets/b7h3/)
- companies: [GT Biopharma](https://onco.cc/companies/gt-biopharma/)

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